Carbon electrode



L'NJ

July 6,1954 w s ET AL 2,683,236

CARBON ELECTRODE Filed Aug. 28, 1950 INVENTORS F RE DER/C K RA WLS JAMES E. MC /NDEN JR.

BY l ATTORNEY Patented July 6, 1954 CARBON ELECTRODE Frederick Rawls, River Edge, N. .L, and James E.

McLinden, Jr., Rego Park, 'N. Y., assignors to' Bendix Aviation Corporation, Teterboro, N. J., a corporation of Delaware Application August 28, 1950, Serial No. 181,824

, The invention relates to electrodes, and more particularly to carbon electrodes of the kind used in vacuum and gas discharge devices.

Although the advantages of carbon electrodes in electronic tubes are well known, difiiculties have been encountered in connecting and mounting the electrical connectors on the carbon without substantial resistance to current flow in passing between the carbon and the connector. The irregular surface of the carbon provides only point contacts between the carbonand the connectors, and because of the small area of the contacting points, the resistance to current flow between the connector and the carbon is relatively high. Also, in tubes of the same type, having electrodes of the same size and shape, electrode resistance varies in the several tubes. In addition, carbon electrodes are easily broken because their mechanical strength is relatively low.

One object of the present invention is to minimize the electrical resistance between the carbon electrode and the connector.

' Another object is to make uniform electrode resistance in tubes of the same type.

Another object is to provide a carbon electrode of greater mechanical strength than those used heretofore and to avoid surface powdering of the carbon, as occurs due to vibration of the electrode, and which may eventually short circuit the tube in Which the electrode is used.

A further object is to facilitate electrically connecting the connectors to the carbon electrode.

Another object is to facilitate supporting the electrode within the tube envelope.

The invention contemplates a novel electrode comprising a carbon core having a thin layer of metal deposited thereon, and a connector connected electrically to the metal layer.

The invention also contemplates a method of manufacturing the .novel electrode comprising depositing the layer of metal on the carbon core by any of several processes, such as electroplating, flame metallizing, arc metallizing, vacuum evaporation or sintering, and electrically connecting the connector to the metal layer by simple contact or by welding, brazing'or soldering, or other suitable means.

The foregoing and other objects. and advantages of the invention will appear more fully hereinafter from a consideration of the detailed description which follows, taken together with the accompanying drawing wherein two embodiments of the invention are illustrated. It is to 2 Claims. (Cl. 313-265) envelope.

be expressly understood, however, that the drawing is for the purposes of illustration and description only, and-is not to be construed as defining the limits of the invention.

In the drawing,

Figure 1 is a perspective View of an electronic tube having a novel grid constructed according to the invention and shown partly in section; and

Figure 2 is a perspective view of an electronic tube having a novel anode constructed according to the invention.

Referring now to the drawings for a more detailed description of the novel electrode of the present invention, the electrode is shown in Figure 1 as incorporated in a gaseous discharge tube having a base I secured to one end of a sealed envelope 3. A cathode 5 is mounted on a conductor 6 extending through the other end of the A press 1 extends from base I within the envelope and mounts a rod-like anode 9 and a novel grid ll constructed according to the invention.

The grid comprises a hollow substantially cylindrical member I3 of carbon surrounding the anode. The inner and top outer surfaces of the grid cooperate with the anode and cathode and the outer circumferential surface of the grid has a layer of metal l5, such as nickel, deposited thereon by one of several processes, such as electroplating, flame metallizing, arc metallizing, vacuum evaporation, sintering, or other suitable means. A connector l1 may be electrically connected to the metal layer by welding, brazing, soldering or other suitable means, or the connector may be urged into contact with the grid by its inherent resilience and provide a suitable electrical connection thereto. A cylindrical insulating element [9 of refractory material having a recess 2| to receive connector I! may surround the grid.

In Figure 2 is shown an electronic tube having a base SI and an envelope 33. A grid 37 is supported by connectors 40 from press 4! of the envelope. A pair of plate-like anodes 45 extend parallel to one another and are positioned at opposite sides of the grid and are supported by connectors 43 from press 4| of the envelope. A filament 35 is supported at one end by connectors 39 from the press and at its other end by arms 39a from one of the anodes. Insulators 38 of glass or other suitable material are interposed in arms 39a to insulate the filament from the associated anode.

The face of each anode adjacent the grid and filament cooperates therewith and the face of each anode remote from the grid and filament has a layer of metal 41 deposited thereon. Connectors 43 may be bonded, as by welding, brazing or soldering W, or otherwise electrically connected to the metal layer.

Electrical resistance between the carbon and the connector is reduced because the nickel layer is deposited in the irregularities on the surface of the carbon and contacts all portions of the associated surface and the resistance to current flow between the metal lay-er and connector is negligible. The metal layer facilities electrically connecting the connector to the electrode and provides greater mechanical strength to the electrode and reduces surface powdering of the carbon.

Although but two embodiments of the invention have been illustrated and described in detail, it is to be expressly understood that the invention is not limited thereto. Various changes can be made in the design and arrangement of the parts without departing from the spirit and scope of the invention as the same will now be understood by those skilled in the art.

What is claimed is:

1. In an electronic tube having an anode, a substantially cylindrical grid surrounding the anode and having a carbon core, a layer of metal deposited on the outer circumferential face of said core, and a connector bonded to said metal layer.

2. An electronic tube having a cathode, an anode, and a substantially cylindrical grid surrounding said anode and positioned adjacent said cathode, said grid comprising a core of carbon having a metal layer deposited on its outer circumferential surface and a connector bonded to said metal layer.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,314,603 Mott Sept. 2, 1919 1,815,390 Young July 21, 1931 1,841,289 Jenks, Jr. Jan. 12, 1932 2,263,164 Dailey 'Nov, 18, 1941 2,513,387 Wei July 4, 1950 

